REVIEW PAPER
Trigemino-cardiac reflex: A recently discovered “oxygen-conserving” response? The potential therapeutic role of a physiological reflex

The trigemino-cardiac reflex (TCR) is defined as a sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea or gastric hypermotility during the stimulation of any of the sensory branches of the trigeminal nerve. The sensory nerve endings of the trigeminal nerve send neuronal signals via the Gasserian ganglion to the sensory nucleus of the trigeminal nerve, forming the afferent pathway of the reflex arc. By this physiological response, adjustments of the systemic and cerebral circulations are initiated to change the cerebral blood flow in a manner that is not yet understood. It appears that the cerebrovascular response to hypoxemia is, to a large extent, due to this reflex and is generated by the activation of neurons of the rostral ventrolateral reticular nucleus; the existence of such endogenous neuroprotective strategies may extend beyond the actually known clinical appearance of the TCR and include the prevention of other potential brain injury states as well.